How do I create a reminder that pops up or tells me that I need to follow-up with a patient on the specified date field?

I looked at the Create Schedule feature. While I can enter the date in the When to Do section, I don't know how to enter the What to Do section.

My goal would be to create a list showing all the follow ups for that day. I would also like to see the scheduled follow ups on a calendar.

Thank you.